CFD–DEM-based study on the effect of different granular bed structures on fine-particle migration characteristics
Abstract
Fine-particle transport in granular beds is strongly governed by pore connectivity and local flow channels. In this paper, the migration characteristics of fine-particle groups in three ordered granular beds are investigated, including square, 45° inclined square, and equilateral triangular arrays. A two-dimensional pore-scale numerical model is constructed with identical porosity, particle properties, and inlet velocity. The temporal distribution of fine particles, penetration ratio, mean particle position, and pressure-drop evolution are compared. The results show that the three structures lead to different preferential transport paths and clogging responses. In the early stage, particles stay near the inlet, and penetration remains close to zero. After entering the bed, particles migrate downward along local channels and accumulate near the outlet. At 2.00 s, the equilateral triangular structure gives the highest penetration ratio (about 0.87), followed by the 45° inclined square structure (about 0.78) and the square structure (about 0.69). The 45° inclined square bed shows the highest initial pressure-drop peak, whereas the square bed maintains the highest late-stage pressure drop. These results indicate that granular-bed arrangement is a key factor controlling particle penetration, retention, and clogging.